Re: [PATCH RFC 55/77] ntb: Update MSI/MSI-X interrupts enablement code

Jon Mason
2013-10-03T01:02:30Z

On Wed, Oct 02, 2013 at 12:49:11PM +0200, Alexander Gordeev wrote:
> As result of recent re-design of the MSI/MSI-X interrupts enabling
> pattern this driver has to be updated to use the new technique to
> obtain a optimal number of MSI/MSI-X interrupts required.
>
> Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
> ---
> drivers/ntb/ntb_hw.c | 41 +++++++++++++----------------------------
> drivers/ntb/ntb_hw.h | 2 --
> 2 files changed, 13 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/ntb/ntb_hw.c b/drivers/ntb/ntb_hw.c
> index eccd5e5..7776429 100644
> --- a/drivers/ntb/ntb_hw.c
> +++ b/drivers/ntb/ntb_hw.c
> @@ -1032,23 +1032,26 @@ static int ntb_setup_msix(struct ntb_device *ndev)
> struct msix_entry *msix;
> int msix_entries;
> int rc, i;
> - u16 val;
>
> - if (!pdev->msix_cap) {
> - rc = -EIO;
> + rc = pci_msix_table_size(pdev);
> + if (rc < 0)
> goto err;
> - }
>
> - rc = pci_read_config_word(pdev, pdev->msix_cap + PCI_MSIX_FLAGS, &val);
> - if (rc)
> + /*
> + * On SNB, the link interrupt is always tied to 4th vector. If
> + * we can't get all 4, then we can't use MSI-X.
> + */
> + if ((rc < SNB_MSIX_CNT) && (ndev->hw_type != BWD_HW)) {

Please check for the HW type first, and then compare to
ndev->limits.msix_cnt (which will be SNB_MSIX_CNT on SNB HW). Also,
put the comment inside the if statement and remove the unecessary "()"
around the comparisons. OCD on my part, but I like it that way.

> + rc = -ENOSPC;
> goto err;
> -
> - msix_entries = msix_table_size(val);
> - if (msix_entries > ndev->limits.msix_cnt) {
> + }

else if...

> + if (rc > ndev->limits.msix_cnt) {
> rc = -EINVAL;
> goto err;
> }
>
> + msix_entries = rc;
> +
> ndev->msix_entries = kmalloc(sizeof(struct msix_entry) * msix_entries,
> GFP_KERNEL);
> if (!ndev->msix_entries) {
> @@ -1060,26 +1063,8 @@ static int ntb_setup_msix(struct ntb_device *ndev)
> ndev->msix_entries[i].entry = i;
>
> rc = pci_enable_msix(pdev, ndev->msix_entries, msix_entries);
> - if (rc < 0)
> + if (rc)
> goto err1;
> - if (rc > 0) {
> - /* On SNB, the link interrupt is always tied to 4th vector. If
> - * we can't get all 4, then we can't use MSI-X.
> - */
> - if ((rc < SNB_MSIX_CNT) && (ndev->hw_type != BWD_HW)) {
> - rc = -EIO;
> - goto err1;
> - }
> -
> - dev_warn(&pdev->dev,
> - "Only %d MSI-X vectors. Limiting the number of queues to that number.\n",
> - rc);
> - msix_entries = rc;
> -
> - rc = pci_enable_msix(pdev, ndev->msix_entries, msix_entries);
> - if (rc)
> - goto err1;
> - }
>
> for (i = 0; i < msix_entries; i++) {
> msix = &ndev->msix_entries[i];
> diff --git a/drivers/ntb/ntb_hw.h b/drivers/ntb/ntb_hw.h
> index 0a31ced..50bd760 100644
> --- a/drivers/ntb/ntb_hw.h
> +++ b/drivers/ntb/ntb_hw.h
> @@ -60,8 +60,6 @@
> #define PCI_DEVICE_ID_INTEL_NTB_SS_HSX 0x2F0F
> #define PCI_DEVICE_ID_INTEL_NTB_B2B_BWD 0x0C4E
>
> -#define msix_table_size(control) ((control & PCI_MSIX_FLAGS_QSIZE)+1)

Good riddance! :-)

> -
> #ifndef readq
> static inline u64 readq(void __iomem *addr)
> {
> --
> 1.7.7.6
>